Effects of Abomasal Infusion of Linseed Oil on Responses to Glucose and Insulin in Holstein Cows

Abstract

The objective was to study the effects of abomasal infusion of linseed oil, a source rich in n-3 C18:3, on whole-body response to insulin (experiment 1) and on insulin antilipolytic effects during feed restriction (experiment 2). In experiment 1, eight nonlactating, non-gestating cows were assigned to a crossover design, fed to meet maintenance requirements, and infused abomasally with either linseed oil (LIN) or tallow (TAL) at a rate of 0.54 g/kg of body weight per d for 5.5 d. Infusions were performed every 8 h during the first 3 d of each period and every 4 h thereafter. Intravenous glucose tolerance tests (IVGTT) were performed on d 5 of each period, followed by i.v. insulin challenges (IC) 12 h later. In experiment 2, six nonlactating, nongestating cows were assigned to a replicated 3 x 3 Latin square design. The experimental protocol included a water (WTR) treatment and feeding was suspended on d 3, leading to 50 and 62 h of feed restriction before IVGTT and IC, respectively. Clearance of glucose during IVGTT and IC was not affected by treatments in either experiment. However, LIN had an insulin sensitizing effect in experiment 1, because a lower insulin concentration led to the same clearance of glucose as TAL. In experiment 1, plasma nonesterified fatty acid (NEFA) concentration was low, reflecting a postprandial state, but NEFA was greater for LIN than TAL during IVGTT (108 vs. 88 +/- 4 microEq/L) and IC (133 vs. 83 +/- 9 microEq/L). In experiment 2, insulin concentrations during IVGTT did not differ across treatments. Basal plasma NEFA concentration before IVGTT tended to be greater for LIN than for TAL (612 vs. 508 microEq/L). Plasma NEFA clearance rate during IVGTT was greater for LIN than for TAL (2.8 vs. 2.5%/min), leading to a shorter time to reach half NEFA concentration (25 vs. 29 min) and greater absolute value of NEFA response area under the curve [AUC; -64,150 vs. -46,402 (microEq/L) x 180 min]. Data suggest that LIN enhanced the antilipolytic effects of insulin. Yet, other factors could have been involved because plasma NEFA concentration before IVGTT was 104 muEq/L greater for LIN than TAL for unknown reasons.

Effects of Feeding Combinations of Soybean and Linseed Oils on Productive Performance and Milk Fatty Acid Profile in Grazing Dairy Cows

“…In LO, linolenic acid content (41.9%, Table 2) resulted lower to the 55% value reported by others [7] [28] [30] but near to values informed in [31] [32]. Linolenic acid in pasture was nevertheless higher than reported by [33] and [30].…”

Colostrum and milk fatty acids of dairy cows as influenced by extruded linseed supplementation during the transition period

“…No such difference was observed in the present study. Pires et al (2008) used feed restriction with dry nonpregnant cows to simulate a period of negative energy balance, as experienced by dairy cows in early lactation. They reported no effect of fat supplementation (water vs. fat) or fat source (linseed vs. tallow) on plasma glucose, NEFA and serum insulin concentrations.…”

Specific fatty acids as metabolic modulators in the dairy cow

“…Two studies showed enhanced whole body response to insulin when rodents were fed fat sources rich in C18:3n-3 (Mustad et al, 2006;Storlien et al, 1991). We hypothesized that changing the FA profile in blood serum of Holstein cows, by enriching its content with C18:3n-3, would enhance whole body response to insulin, potentially increasing insulin antilipolytic effects during periods of negative energy balance (Pires et al, 2008). One experiment was conducted to study the effects of abomasal infusion of linseed oil, a source rich in C18:3n-3, on whole-body response to insulin.…”

“…(Mashek et al, 2005) and abomasal infusions (Pires et al, 2008), and whether limited flow of these FA to the duodenum might have impacted biological responses in studies involving periparturient cows (Andersen et al, 2008;Mattos et al, 2004;Moussavi et al, 2007a;Petit et al, 2007).…”